function gewCameraSystem() 
{
  this.m_camera_list = [];
  this.m_active_camera = null;
}

gewCameraSystem.prototype.createCamera = function(camera_constructor,
                                                  parent_node,
                                                  param1,
                                                  param2,
                                                  param3,
                                                  param4)  
{
  var camera = new camera_constructor(param1,param2,param3,param4);
  this.m_camera_list.push(camera);  
  parent_node.appendChild(camera);  
  return camera;
};

gewCameraSystem.prototype.removeCamera = function(camera) 
{
  for (var i = 0; i < m_camera_list.length; ++i) {
    if (m_camera_list[i] === camera) {
      this.m_camera_list.splice(i, i + 1);
    }
  }
};

gewCameraSystem.prototype.getCameraNumber = function() {
  return this.m_camera_list.length;
};

gewCameraSystem.prototype.getActiveCamera = function() {
  return this.m_active_camera;
};

gewCameraSystem.prototype.setActiveCamera = function(camera) {
  this.m_active_camera = camera;
};
